Bernhard Kress – WearIA13

Google Confidential and Proprietary

Diffractive and holographic optics as combiners in Head Mounted Displays.

ISWC Zurich 2013

Bernard Kress ([email protected])


Outline

1)  Introduction to optical combiners for see-through displays

2) Conventional optical combiner architectures

3) Diffractive and holographic combiner architectures

4) What else can diffractives offer for wearable computing?


1) Pupil forming architecture

2) Non -pupil forming architecture (magnifier) - Glass

There are two main optical architectures we can built upon:


Most of these architectures have been developped since the 70s especially for rotary wing aircraft HMDs


See through optics

Available optical combiner technologies


See through optics

Free space architectures


See through optics


Light guide architectures


See through optics


Waveguide architectures

Light guide architectures


Free space optical combiner technology

Arrayed or cascaded combiners

Curved combiners

Flat combiners @< 45deg

Classification of optical combiners along functionalities 1- Free space and guided space architectures

Flat combiner @ 45deg

Free form TIR combiners


Half tone mirror



Curved combiners




Beam splitter


45 degrees combiner in vertical direction


Another example of 45 degrees combiner


Vertical 45 degrees wide FOV combiner example (Laster)


GlassUp’s combiner


Vuzix’s Smart Glass M100


Google Glass: 45 degrees flat combiner in horizontal direction


Use of phase conjugate material



Curved combiners




Flat reflective lens


Flat beam deflector Off-axis flat lens



Curved combiners





The notion of « Bug Eye » in optics


Implementing the off-axis imaging task– aspheric profiles


« Bug-eye » reflective combiner – ODA Labs


« Bug-eye » reflective combiner – Laster


Occulus rift occlusion « Bug eye » version


Sony’s HMZ T2 3D glasses – for gamers


Digilens / Virtuality example of curved combiner and off-axis holographic relay lenses


Arrayed reflectors


Curved combiners







Curved combiners





TIR free form surfaces with see through corrector


Example of TIR / free-form surfaces combiner


Verizon/Kopin’s Golden-i and Canon’s implementations examples of TIR free form optical combiners


Verizon/Kopin’s Golden Eye


Guided wave optical combiner technology

Holographic extractors Diffractive extractors

Classification of optical combiners along functionalities 2- Guided wave architectures

Cascaded mirrors combiners

Dynamic extractors



Holographic extractors Diffractive extractors


Dynamic extractors

Micro-mirrors array


Epson Moverio light guide tilted mirror combiner


Cascaded dichroic mirrors: Lumus LOE


Lumus LOE monocular and binocular 3D see through display


Optinvent light pipe arrayed prisms architecture



Holographic coupler / extractors

Diffractive coupler / extractors


Dynamic extractors

Leaky gratings Incoupling grating


Holographic optical elements (HOEs) Sanwiched “goop” with index modulation

Diffractive optical elements (DOEs) Surface relief modulation


Holographic optical elements (HOEs) Sanwiched “goop” with index modulation

Diffractive optical elements (DOEs) Surface relief modulation

Beam splitter Engineered diffusers Grating / Beam redirection CGH (custom pattern projection)

DOE / aspheric lenses Micro lens arrays (MLAs) Beam shaping / beam homogenizing


Hologram type Angular selectivity Spectral selectivity

η (%) @550nm

α (°)

η (%) @550nm

λ (nm)

η (%) @30°

α (°)

η (%) @30°

λ (nm)

Transmission hologram

Reflection hologram

30 60 0 550 650 450

30 60 0 550 650 450

100 100

100 100

Spectral and angular Bragg selectivity in reflective and transmission volume Holograms


Kogelnik model for Bragg selectivity in volume holograms



Vuzix / Nokia Waveguide diffractive combiner (with laser pico projector)


Example of Exit Pupil Expander in 2 directions


Example of Vuzix’s diffractive see through combiners (mock-up devices)






Dynamic extractors

Leaky reflective holograms IncouplingTIR hologram Leaky transmission holograms Incoupling TIR hologram


Example of SONY reflective holographic combiner

Uses guided space and super-imposed RGB reflective volume holograms. Horizontal design.


Example of KONICA/MINOLTA volume holographic combiner

Uses guided space and single reflective hologram with multiple RGB exposure. Vertical design.






Dynamic extractors

Dynamic holographic extractors Incoupling hologram


… and a few odd balls which cannot be classified


Olympus’ opaque see- through HMD using tapered light guide and 45 degrees mirror combiner

The combiner (tappered light guide) is smaller than the eye pupil therefore producing a see-through effect.


Switchable hologram HMD for time / field sequencing (Univ of Strasbourg / SBG Labs)


Innovega diffuser glasses and contact lens combo


Innovega compound HMD


Comparative analysis of combiner optics


Gesture sensing via diffractive optics


… try to look less like this…


… but more like this!!


Projector Camera

CPU

Traditional weaponery used for 3D scanning via structured illumination using multiple fringe projection


Diffractive projectors are small and cheap


… with more complex structured illumination…

CGH structures as under microscope

Projected code pattern

Zoom on patterns / non-repeating 3x3 codes


Primesense KINECT: Two cameras (visible and IR) and a diffractive projector

IR camera Visible camera

Laser + diffractives assembly

Temp sensor and Peltier cooler


Dual diffractives package assembly -> producing optical convolution between a CGH and a crossed grating


zoom

Pattern generator CGH microscope pictures.


Sam

e spot patterns (rotated by 180 degrees)

Binary CGH pattern

Zero order

Single tile pattern projection from CGH element

Spot pattern on scene


Two examples of Epson Moverio binocular see through displays linked to Kinect Primsense gesture sensor (presented at AWE 2013)


First generation Primesense Kinect sensor

Second generation Primesense sensor

Target size of wearable projector / sensor


How small can one make the projector elements?

Static 8 pattern diffractive projector window


Surface topology scan over structured light pattern generator etched in quartz window

1 µm


Example of virtual interface projection with simple structured illumination from previous piece of quartz.

IR camera

RGB camera


The key is to produce smarter optics and as a result reduce signal processing requirements

- smaller, faster, cooler, cheaper -

Signal processing Optics

Signal processing Smart Optics

Signal processing « Smarter » Optics

Canesta TOF

Primesense Kinect

What is needed for HMDs

Signal processing Optics LeapMotion



Documents

Bernhard Kress – WearIA13